Control Of Corner Transverse Crack In Continuous Cast Slab Of Low Carbon Steel

Corner transverse crack defect,which is commonly found in the continuous casting lines,is one of the main defects of Baosteel’s low carbon steel(C:0.04%～0.25%)and low carbon micro-alloyed steel(including Nb,V,Ti and so on).Such defects on the slabs would cause steel roll edge crack or become warped skin defect in hot rolling process,resulting in relegation or scrap steel coil.The slabs with defects therefore are offline for cleaning and cutting angle by manual effort before the hot-rolled process.All these additional processes decrease the delivery efficiency seriously and raise the product cost inevitably.In this study,the low carbon steel produced in No.1 continuous caster in Baosteel were taken as raw material.The effects of hot metal composition,casting speed,mold oscillation on the corner transverse cracks are investigated.Additionally,the influences of cooling parameters,secondary cooling pattern and the roll gap displacement are also discussed.A promising process for controlling the corner transverse cracks of low carbon steel is finally proposed.The main conclusion are summarized as following:The carbon content in hot metal had significant influence on the corner transverse corner cracks.The cracks obviously aggravated when the carbon content of the steel is in the range of 0.09～0.16%.Moreover,the elevation of nitrogen content would aggravate the cracks as well.The other micro-alloy compositions in hot metal also effected the corner transverse cracks.Suitable casting speed and vibration parameters could alleviate the slab corner crack.For the same kind of steel,the increase of radian deviation and roll gap deviation would aggravate the corner crack.Furthermore,the decrease of the deviation and the appropriate mould flux are both beneficial for the control of slab corner crack.